[relmers]

I bought a new ignition/door lock(s) for my '66 GTO and the keys that came with them were marked with an "A" on the stem. I've looked online to get additional keys and have come across similar old style octagon GM keys marked with "C" that look the same. My question, is there a difference between the two and if so, what is the difference?

Thanks!!!

Bob

[65Mark]

GM used the B10 key blank for ign. and doors, and the B11 for trunk and glovebox from 1936 to 1966. In 1967 they changed to B40 or B42 I think. Memory isn't that good on the 67 and later. 67 is also when they went away from the octagonal shaped key to the rectangle shaped key.

The difference is in the keyway. Look at the grooves on the side of the key.

[1967SC]

Originally Posted by 65Mark

GM used the B10 key blank for ign. and doors, and the B11 for trunk and glovebox from 1936 to 1966. In 1967 they changed to B40 or B42 I think. Memory isn't that good on the 67 and later. 67 is also when they went away from the octagonal shaped key to the rectangle shaped key.

The difference is in the keyway. Look at the grooves on the side of the key.

I thought it was for the model year 1968 that they changed over to the square key for the colum mounted ignition switch.
My mother got a brand new LeMans Sarari Wagon that year in Verdoro Green with the wood panels.

I just re read your post. I that is what you meant to say.

[65Mark]

Just to clarify... The 67 key is different than the 1966 and earlier. !967 was the first year for the square and oval keys (ign and trunk)

[fyrffytr1]

Here are the keys to my 67 door and ignition. Just got them from our host.

[Satyr1966]

'67 keys looked almost the same as '66 keys but they wouldn't fit in the locks. The grooves were different.

[azkeebler]

Unfortunately, the aftermarket locks use the newer keyways, yet include the octagonal key blanks as a disguise. If you have an "A" stamped, you are looking for a square-head B-50 blank as a replacement. However, many aftermarket cylinders are universal and allow the other keyways to enter(which is why I shy away from them). If this is the case, you may get away with ordering the B-10,B-11 blank.

I ran into this problem with the aftermarket cylinders when I was a locksmith.

[squidtone]

I just ran across this in my 1967 Pontiac Shop manual.
On page 0-4, it discusses the new keys used for 67. It says they use new keyways and increased number of biting depths compared to 66 and older keys.

However, despite being new type keys (keyways), they have an illustration of the key shape, and they are the classic octagon for the ignition, the "A" key, and the "B" key is round for the door, trunk and glove compartment.

It goes on to explain how to determine your key code by looking at your key and comparing it to the positions listed in the manual.

[6704gto]

68 had the igntion still in dash and they switch over to the colum in 69,i beleive that is when the square key showed up

[YNOBIL]

From 1935 to 1966 the shafts of the keys were the same for all keys. On these keys the door and ignition key was octagon and the trunk and glove box key was pear shaped. These keys had no letter designation on them. Beginning in 1967 the octagon ignition key had a new shaft shape and had an "A" designation. The trunk key an entirely different shaft design but was still pear shaped, it was given a "B" designation. In 1968 they kept the octagon and pear shaped, but created two new shaft designs. The octagon was a "C" key and the pear shape was a "D" designation. As we all know in 1969 GM moved the ignition switch to the steering column. This is when they switched to the square ignition and round trunk keys. They came up with a new shaft design for the square igntion and coded it "E". The round trunk became "F". From then on they stuck with the square and round keys. In 1970 they created a fourth shaft design with a new set of letters. In 1971 they stayed with the square and round styles but repeated the 'A" & "B" shaft design of 1967. In 1972 they repeated the "C" & "D" shaft design. I don't know what they do these days, but they rotated those four key series for years. Let me clarify I am refering to GM parts when I discuss key codes not aftermarket. I have the original GM part numbers if needed.

[GT182]

Originally Posted by 6704gto

68 had the igntion still in dash and they switch over to the colum in 69,i beleive that is when the square key showed up

Correct, square key appeared in 69 for the column mounted ignition switch. Large round key for the trunk.

[azkeebler]

Originally Posted by YNOBIL

From 1935 to 1966 the shafts of the keys were the same for all keys. On these keys the door and ignition key was octagon and the trunk and glove box key was pear shaped. These keys had no letter designation on them. Beginning in 1967 the octagon ignition key had a new shaft shape and had an "A" designation. The trunk key an entirely different shaft design but was still pear shaped, it was given a "B" designation. In 1968 they kept the octagon and pear shaped, but created two new shaft designs. The octagon was a "C" key and the pear shape was a "D" designation. As we all know in 1969 GM moved the ignition switch to the steering column. This is when they switched to the square ignition and round trunk keys. They came up with a new shaft design for the square igntion and coded it "E". The round trunk became "F". From then on they stuck with the square and round keys. In 1970 they created a fourth shaft design with a new set of letters. In 1971 they stayed with the square and round styles but repeated the 'A" & "B" shaft design of 1967. In 1972 they repeated the "C" & "D" shaft design. I don't know what they do these days, but they rotated those four key series for years. Let me clarify I am refering to GM parts when I discuss key codes not aftermarket. I have the original GM part numbers if needed.

Correction, there was no "F" blank. The corresponding trunk key for the "E" blank was "H". Made no real sense, but it is what it is.

No matter how or what GM did originally, the aftermarket suppliers don't follow the corresponding blanks used to their relative application. A non-GM reproduction '62 ignition cylinder will not have the B-10 octagon keyway.

To make things even more confusing, fleet vehicles (u-hauls) and police or government vehicles used round head keys for all their locks or exclusive blanks all their own. Even back in the '30's.

[YNOBIL]

Originally Posted by azkeebler

Correction, there was no "F" blank. The corresponding trunk key for the "E" blank was "H". Made no real sense, but it is what it is.

No matter how or what GM did originally, the aftermarket suppliers don't follow the corresponding blanks used to their relative application. A non-GM reproduction '62 ignition cylinder will not have the B-10 octagon keyway.

To make things even more confusing, fleet vehicles (u-hauls) and police or government vehicles used round head keys for all their locks or exclusive blanks all their own. Even back in the '30's.

Thanks for the update. For some reason my GM Parts books only list the keys by year and didn't list the letter codes on the keys. Went down to my basement and found some new GM lock sets and keys. The 4th sequence was "J" Ign and "H" trunk. Also, don't know what year but at some point they started keying the doors to match the trunk instead of the ignition so a thief couldn't pull a door cylinder out and make an ignition key (That's how my 3 month old 72 GTO was stolen).
And you're right about fleet cars. Way way back in 1967 I had a job at the Ford Plant in Chicago installing trunk lock assemblies in new Galaxie's and when a Chicago Police Car came through there would be a special lock set for it.